Well...magnetic field lines are generally not parallel....they form the closed loops.......but they never intersect each other......'this is b'cuz we define the direction of magnetic field lines to be the direction in which North pole of a compass points.....nd' if they'll intersect that will mean that there's 2 north pole.....nd'u know it's not possible....that's it!!

Introduction:
Magnetic field lines are used to represent the direction and strength of a magnetic field. These lines are continuous and form closed loops that emerge from the north pole of a magnet and re-enter through the south pole. Inside a magnet, the magnetic field lines are parallel to each other, and this can be explained by considering the behavior of magnetic dipoles.

Magnetic Dipoles:
Magnetic materials, such as magnets, are made up of countless tiny atomic magnets called magnetic dipoles. These dipoles consist of a north and south pole, similar to a tiny bar magnet.

Alignment of Magnetic Dipoles:
Inside a magnet, the individual magnetic dipoles are aligned in such a way that their north poles point in the same direction. This alignment occurs due to the interactions between neighboring dipoles and the influence of an external magnetic field.

Formation of Magnetic Domains:
The alignment of magnetic dipoles results in the formation of regions called magnetic domains. In each domain, the dipoles are uniformly aligned, creating a net magnetic field in a specific direction. The boundaries between these domains are known as domain walls.

Uniform Magnetic Field:
Inside a magnet, the magnetic field lines emerge from one end (north pole) and re-enter through the other end (south pole). These field lines follow the path of least resistance, which is along the aligned dipoles within each magnetic domain. As a result, the magnetic field lines inside the magnet become parallel to each other.

Domain Wall Behavior:
When an external magnetic field is applied to a magnet, it can influence the alignment of the magnetic dipoles and cause the domain walls to move. This movement results in a reorientation of the magnetic domains, leading to changes in the overall magnetic field of the magnet.

Conclusion:
In summary, the parallel alignment of magnetic field lines inside a magnet is a consequence of the arrangement of magnetic dipoles within magnetic domains. The uniformity of magnetic domains allows for the magnetic field lines to follow a parallel path, resulting in a well-defined and consistent magnetic field inside the magnet.